Most often, a band of little musical talent or significance whatsoever. Usually, the type of band which your one crazy, musically incompetent friend listens to and rips guitar tab from off the internet in an attempt to impress others who could not tell the difference between a Really Shit Band and the sound of their own head imploding from horrible sounds the rest of us are subjected to.
I kickedMark in the balls and he sounded like a Really Shit Band.
A bog-standard, charisma-deficient, boring-shouty-guitar-rock "indie" band propelled to undeserved stardom through favourable reviews/coverage in the NME, a once-great, now-rubbish music weekly.
Sadly, in the UK, many people consider these bands to be the definition of indie.
Kasabian, Hard-Fi, The Kooks, Babyshambles, The Arctic Monkeys, Bloc Party, Razorlight: shit NME bands.